This invention concerns primarily but not exclusively the seats of automobile vehicle, and in this case more specifically front seats whose seat pan includes means for producing a massaging effect on the occupant.
We already know of seats featuring mechanisms in the seat pan that create vertical, transverse or longitudinal vibrations or oscillations, with the aim of transmitting these movements to the user through the seat pan padding to produce a massaging effect.
These mechanisms more specifically meet the already stated desire to create upward subcutaneous massaging under the thighs to prevent the sensation of xe2x80x9cpins and needlesxe2x80x9d that can arise when driving for long periods.
Furthermore, the need to maintain a good posture of the lower vertebrae is generally well known, as are the benefits of maintaining micro-movements of the vertebral column.
The known mechanisms satisfy these desires at least in part, but none of them can correct a poor initial posture, or one that is acquired gradually, for example by the pelvis sliding forwards.
The aim of this invention is to solve this problem and more specifically to bring the user""s pelvis back into the correct position, either on demand or more or less automatically, while at the same time creating an additional alternating upward massaging effect under the thighs and small movements of the lower part of the vertebral column.
With these objectives in mind, the subject of the invention is an automobile vehicle seat pan containing a reinforcing frame carrying a suspension lattice and means for creating oscillatory movements in the seat pan, characterized in that the suspension lattice is made in two sections separated along a median vertical plane dividing the seat into a right-hand (RH) side and a left-hand (LH) side, each section of the lattice being linked to specific means for generating a cyclic movement including, in an upper portion of its travel, a rearward movement of translation, and in that it includes control means for generating the said movements with an angular phase difference between the two sections.
The rearward movement of each part of the lattice when in the upper position has the corresponding effect of pushing the zone around the ischium, that is to say the buttock that rests on the said part of the lattice, rearwards i.e. towards the seat back. This effect is all the more marked that when one of the buttocks is thus raised and pushed rearward by the movement of the part of the lattice situated on the same side, the load is taken off the other buttock, facilitating the forward return movement of the second part of the lattice, which is then in the lower position.
In seats in which the supporting lattice is covered by padding, the padding is also in two parts corresponding to the respective sections of the lattice, the movement of which causes a similar movement in the part of the padding that it supports.
Globally, each ischium is therefore subjected cyclically to a rearward force, while the other is subjected to a much lower force in the forward direction or even no force at all. This therefore results in the gradual repositioning of the lower part of the pelvis, accompanied by a slight lateral swaying of the pelvis, creating the desired micro-movements of the vertical column mentioned earlier. An alternating massaging effect beneath the thighs and directed towards the top of the thighs, takes place at the same time.
The amplitude of the movement is of course limited to avoid creating excessive lateral swaying of the pelvis.
Preferentially, the cyclic movement is a movement of translation that is more or less circular around a horizontal transverse axis common to the means of generating the said movement in each section of the lattice, the direction of rotation being such that during the upper portion of the travel, the movement is towards the rear.
Also preferentially, to obtain the desired movement of each section of the lattice, each of the two sections can be elastically deformed in the longitudinal direction, with the two sections of the lattice being attached at the front to the same line which is fixed with respect to the reinforcing frame, and at the rear to crankshafts that are rotated in such a way as to maintain an angular phase difference of 180xc2x0 during the movement.
When stopped, the two crankshafts, or other means of generating the circular movement, are maintained in the same angular position, that is to say in the same position of the cycle, so that the left-hand section and right-hand section of the lattices are in the same plane and in the forward position, with the whole of the seat pan then being at the same level
Practically, when the cyclic movement is stopped, in particular when the user leaves the seat, the movement of each part of the lattice stops when it reaches more or less the maximum forward position, with one of the two half-lattices reaching this position half a cycle after the other.
Thus, when the seat is empty, the two sections of the lattice are in this forward position. According to a preferential arrangement, the seat pan features means for initiating a preliminary positioning phase when a passenger occupies the seat again. In this phase, the two sections of the seat pan are driven simultaneously rearwards to move the user""s posterior backwards with the aim of facilitating from the outset the adoption of a good posture, especially of the vertebral column, by pushing the entire pelvis towards the seat back. From this position of simultaneous backward movement of the two sections of the seat pan, the cyclic out-of-phase movement can be started again, either automatically or on demand, with the movement of one of the two sections starting half a cycle behind the other section.
The crankshafts can be driven by independent motors slaved to maintain the said angular phase difference in the movement.
The crankshafts can also be driven by a single motor, in which case the two crankshafts are linked in rotation, for example by an angular travel stop system that ensures the said 180xc2x0 angular phase difference during rotation in one direction, but also enables this phase difference to be eliminated by rotation of the motor in the opposite direction to return to the rest position indicated above when stopped.
Typically, when the lattice is covered by padding, each half-lattice is formed of metal wires bent in a zigzag or alternating hairpin arrangement in the plane of the lattice, conferring the desired elasticity upon it. The front ends of these wires are all attached to a fixed element of the reinforcing frame, on which they can pivot slightly more or less around a common axis. As the rear ends of the lattice wires are pivot-mounted on the crank of a crankshaft, its rotation causes a corresponding circular displacement of the rear ends of the half-lattices, which is transmitted along the whole of each half-lattice thanks to their elasticity, although it reduces gradually towards the front of the half-lattice because the front is fixed.
Preferentially, when the seat pan includes padding that covers the lattice, each section of the padding, conventionally made of polyurethane foam, for example, features transverse slits that increase the deformation capacity of each half-padding, to better follow the cyclic elongations of the half-lattices on which they rest.
Also preferentially the seat pan can include an external covering that ensures greater adherence when it moves rearwards than when it moves forwards. Such a covering, typically of a seal-skin or fish-scale type material, ensures better adherence of the seat pan under the occupant""s posterior during the rearward movement, and favors sliding during the forward movement.
To automate operation, the seat pan preferentially features pressure sensors under the seat pan surface to measure the pressure exerted by the occupant""s buttocks.
As the pressure sensors are positioned such that they can measure the pressure exerted on the seat pan surface at a minimum of two points situated one in front of the other; they can then control automatic stopping of the crankshaft driving motor(s) when the measured pressure, or the pressure differential between a sensor situated the furthest to the rear and another sensor situated further forward, reaches a predetermined threshold indicating that the weight of the seat occupant is once again distributed on the seat in a configuration of optimum comfort. Similarly, the sensors can cause automatic activation of the system if they detect that the area of highest pressure has moved abnormally towards the front of the seat, and also initiate automatic starting of the preliminary positioning phase when they detect the arrival of an occupant, or automatic moving of the two sections of the lattice to the forward position when they detect departure of the occupant.
To fulfill these automatic functions, the seat may be equipped with means for storing the values of the pressure or of a pressure differential, and means for comparing the values measured by the sensors with the stored values, for different users for example.
Other characteristics and advantages of the invention will appear in the following description of an automobile vehicle seat in compliance with the invention.